Bending press



March 22, 1966 R. F. GloRDANo BENDING PRESS 9 Sheets-Sheet l Filed Nov. 6, 1961 .Sq ,NSR @f March 22, 1966 R. F. GIORDANO 3,241,350

BENDING PRESS Filed Nov. 6, 1961 9 Sheets-Sheet 2 F/ 3 Pie/0l@ ABT ff; ull

INVENTOR.

March 22, 1966 R. F. GIORDANO 3,241,350

BENDING PRESS Filed Nov. 6, 1961 9 Sheets-Sheet 5 March 22, 1966 R. F. GIORDANO BENDING PRESS 9 Sheets-Sheet I.

Filed NOV. 6, 1961 ber-m7 March 22, 1966 R. F. GIORDANO BENDING PRESS 9 Sheets-Sheet 5 Filed Nov. 6, 1961 FIG/4 March 22, 1966 R F GlORDANO 3,241,350

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INVENTOR.

R. F. GIORDANO March 22, 1966 BENDING PRESS 9 Sheets-Sheet 7 Filed Nov. 6, 1961 March 22, 1966 R. F. GIORDANO 3,241,350

` BENDING PRESS Filed Nov. 6, 1961 9 sheets-sheet a p INVENTOR.

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BENDING PRESS Filed NOV. 6, 1961 9 Sheets-Sheet 9 INVENTOR. rea?. o f's United States Patent O BEN DIN G PRESS Roger Franois Giordano, Deuil-la-Barre, France, assignor of one-half to Promecan Sisson-Lehmaun, So-

ciete Anonyme, Saint-Denis, France Filed Nov. 6, 1961, Ser. No. 151,415 Claims priority, application France, Sept. 5, 1955, 698,478; July 1'7, 1956, 57,439 17 Claims. (Cl. i2- 412) The present application is a continuation-in-part application of my U.S. Patent No. 3,007,508, filed September 5, 1956, and entitled, Sheet Metal Bending Press.

The bending press disclosed in my U.S. Patent No. 3,007,508 includes a hydraulically operated member which moves along a central line of symmetry of a movable press member so that the same is moved toward a stationary press member. A pair of stationary guide members is provided along the central line of the movable press member and are engaged by two pairs of guide rollers which are resiliently supported on the movable press member. Consequently, when the forces acting on the bending edge of the movable press member during a bending operation, are not uniformly distributed 'along the bending edge, the movable press member tends to perform a slight lateral or tilting movement. However, Since both pairs of guide rollers are resiliently supported, the resilient guide means do not dene an exact pivot axis for the movable press member. Consequently, the displacement of the movable press member cannot be accurately controlled, or limited by feeler means, such as limit switches.

It is one object of the present invention to provide a bending press in which a movable press member is supported for a tilting movement about a pivot axis while being resiliently guided in the region of a center line thereof.

Another object of the present invention is to provide a bending press in which the actuating force is applied along a center line of the movable press member so that the bending edge of the movable press member is bent under load to assume a curved shape substantially parallel to the shape to which the stationary press member is bent under load.

Another object of the present invention is to provide a bending press in which the movable press member is guided in the region of the center line thereof for movement in a working direction perpendicular to its bending edge while being pivotable labout an axis perpendicular to the center Iline and to the bending edge.

Another object of the invention is to provide feeler means for sensing an undesired tilted position of the movable press member when the same turns about its pivot axis during a pressing operation, and to use such feeler means for stopping the machine.

Another object of the present invention is to provide adjustable stop means for defining the terminal positions of the movable press member while cooperating with hydraulic means which effect the movement of the movable press member.

Another object of the present invention is to provide additional hydraulic moving means for the movable press plate, which are symmetrically arranged with respect to the center line along which the main hydraulic moving means of the press operate.

With these objects in view, one embodiment according to the present invention comprises, a support; a stationary press plate; a movable press plate having a pressing edge confronting a corresponding substantially parallel pressing edge of the stationary press plate; moving means, preferably a hydraulic cylinder and piston means, operable in the direction of a central line of symmetry 3,241,350 Patented Mar. 22, 1966 substantially normal to the edge of the movable press plate and engaging the movable press plate only in the center region thereof for moving the movable press plate toward the stationary press plate; first and second stationary guide means extending in a working direction substantially normal to the edge of the movable press plate and being spaced from each other; and rst and second movable guide means carried by the movable press plate and ibeing disposed to cooperate with the rst and second guide mean-s, respectively for guiding the movable pressl plate in the working direction.

In accordance with the present invention, only one of the movable guide means is resilient, preferably the upper guide means which is located nearer to the press edge of the movable press plate, while the other movable guide means is rigid, and preferably has a pair of rollers engaging the respective stationary guide means in such a manner as to support the movable press plate during movement in the working direction for pivotal movement about an axis transverse to the edge of the press plate and to the working direction. In this manner, unequal forces acting on the edge of the movable plate` tend to tilt the movable press plate about the axis dened by the guide means, while the resilient lguide means, yield. However, when such tilting movement exceeds a predetermined extremely small angle, feeler means sense such undesired tilted position of the movable pressrplate, and effect stopping of the moving means by which lthe movable press plate is operated, so that the same stops.

'In a modified embodiment, two force-transmitting members are hydraulically operated and located spaced along the central -lineV of the movable press member, According to another modification, two hydraulic moving means are` symmetrically arranged in lopposite sides of the central ICC r line of the movable press plate and exert forces on the same in the region of the ends of the press edge of the movable press plate. This embodiment is prepared when very great bending forces are to be exerted on a workpiece.

In the preferred embodiment of the invention, the hydraulic moving means for the movable press plate include a cylinder having a pressure chamber `and a discharge chamber separated by a piston acting on the press plate. A valve is provided on the piston,V and opens a passage connecting the chambers in the cylinder when a rod connected to the valve engages an adjustable stop during the working stroke of the movable press member, so that 4the same stops in a terminal position selected by adjusting the adjustable stop.

The other terminal position of the movable press plate is also adjustable, and hydraulic damping means are provided for slowing down the last part of the return stroke of the movable press member which is eifected by .the force of gravity after the pressure chamber of the moving means has been relieved under control of the operator.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages. thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which:

FIG. 1 is a front view of a press according to one ernbodiment of the invention, with a front plate omitted for the sake of clarity;

FIG. 2 is a side view of the embodiment shown in FIG. 1;

FIG. 3 is a fragmentary sectional view along line 3 3 in FIG. 1, as viewed in the direction of the arrows, but on an enlarged scale;

FIG. 4 is a fragmentary front view on an enlarged scale taken on line 4-4 -in FIG. 3;

FIG. 5 is a front view, partly in section, illustrating a detail of the embodi-ment of FIG. 1 on an enlarged scale;

FIG. 6 is a fragmentary schematic front view of a modified embodiment, with a front plate omitted for the sake of clarity;

FIG. 7 is a horizontal sectional view on an enlarged scale taken on line 7-7 in FIG. 6;

FIG. 8 is a schematic front view of a detail of the embodiment of FIGS. 1 and 2;

FIG. 9 vis a diagram illustrating the distribution of forces in the stationary press member of the embodiment 0f FIGS. 1, 2 and 8;

FIG. 10 is a diagram corresponding to FIG. 9 but showing the stationary press member deformed by the stress of a pressing operation;

FIG. 11 is a front view of another embodiment of the invention;

FIG. 12 is a side View, partly in section taken on line 12-12 in FIG. 1;

FIG. 13 is a front view of another embodiment of the invention;

FIG. 14 is a front view of another embodiment of the invention;

FIG. 15 is a vertical sectional view of a resilient guide means used in the embodiments of FIGS. 11, 13 and 14;

FIG. 16 is a front view of the rigid guide means used in the embodiments of FIGS. 11, 13 and 14;

FIG. 17 is a fragmentary sectional view taken on lines 17--17 in FIG. 11, and showing a detail on an enlarged scale; and

FIG. 18 is a fragmentary diagrammatic view illustrating the hydraulic circuit of the embodiment of FIG. 14, which is used in all embodiments of the invention with minor adaptations.

Referring now to the drawings, and more particularly lto FIGS. 1 and 2, a support 1 includes a lower base part, and two upright posts 2 and 3 on which an upper stationary press member 4 is mounted. Press member 4 includes a pair of outer plates 4a on opposite sides of an inner plate 4b which carries the press tool S. A plate 6 is secured to support 1, and another cover plate 7 is secured to plate 6 and to the upright posts 2 and 3 by conventional means, and -may also be connected to plate 6 =by prismatic blocks 8.

Several blocks 8 are provided, as best seen in FIG. 1 and on each block, 8, two pairs of rollers 9 and 10 are rotatably mounted spaced from each other so as to be located on opposite sides of a movable press plate 11. Press plate 11 has slots 12 through which blocks S pass, and along slots 12, pairs of guide bars 13 are secured to opposite sides of the movable press plate 11, so that rollers 9 and 10 Will roll on the `guide bars 13 during vertical up and down movement of the movable press plate 11. A press tool 14 has a longitudinal groove 1S cooperating with press tool 5 so that a flat workpiece located between the longitudinal edge faces of tools 5 and 14, will be bent into angular shape.

If tools 5 and 14 are made to closely approach each other, the bent portions of the workpiece will dene a right angle, but if press tool 14 is not moved up so far, an obtuse angle will be formed in the workpiece. A foot operated lever 16 is mounted on the machine, and is used by the operator to control the operation of the movable press member, as will be explained hereinafter in greater detail.

The movable press member 11 has two cutouts 17 and 18 which are located in the vertical plane of symmetry of the movable press plate 11. Two stationary `guide members 19 and 20 pass through cutouts 17 and 18 and are fixedly secured to plates 6 and 7. In the embodiment of FIGS. 1 and 2, guide member 19 is a prismatic block having lateral parallel guide faces 19a, while guide member 21B is also of prismatic shape and has parallel guide faces 26a, but has an inner cylindrical chamber 21 in which a piston 22 is located. A pump supplies an operating liquid to the lower pressure chamber of cylinder 21, while the liquid is discharged from the upper discharge chamber during the pressing strokes of the press plate 11 in a manner which will be described hereinafter in greater detail. A force-transmitting member 23 is iixedly secured to the piston 22 and passes upwardly through a central opening in the top of the hydraulic cylinder 20, 21. The upper end of member 23 abuts the upper edge of cutout 18, so that press plate 11 will be raised when piston 22 moves in upward direction. Forcetransmitting member 23 -is also arranged in the central line of symmetry of press plate 11.

Two pairs of resilient guide means 24 and 25 are mounted on press plate 11 to respectively cooperate with the stationary guide means 19 and with the stationary guide means 29. The resilient guide means of each pair are arranged symmetrical with respect to the central line of symmetry of press plate 11, and include pairs of rollers 26 and 27 which roll on the stationary guide means 19 and 2t? when the movable press plate 11 moves toward the upper press plate 4, or away from the same in downward direction. Resilient means 36 bias rollers 26 and 27, as is best seen in FIGS. 3 and 4.

As shown in the fragmentary front View of FIG. 4, the press plate 11 has a cutout 11a in which resilient guide means 25 is located. A bracket 30 is secured to press plate 11 and extends across the cutout 11a. A shaft 31 has a fixed flange 32, and a threaded portion 33 on which a nut 34 is mounted. A washer 35 is provided between nut 34 and supporting bracket 30, so` that by turning of nut 34, two pairs of cup-shaped springs 36 are pressed by flange 32 against bracket 30, and resiliently tensioned. Shaft 31 has a knife edge which is located in a corresponding groove 37 at the center of a shaft 38 which has two dat surfaces 38a and 33h. Shaft 38 is non-turnably mounted in a matching cutout 39 of a slide member 41) which i-s mounted on press plate 11 for sliding movement toward and away from the stationary guide means 20.

Shaft 38 carries the rollers 27 at its end portion, and as shown in FIGS. 3 and 4, rollers 27 are circular ball bearings whose inner part are secured to shaft 38, while the outer parts are freely rotatable, and roll without friction on the guide faces 20a of stationary guide means 20.

Resilient means 36 are pre-tensioned by nut 34 when shaft 31 is adjusted by nut 34 to hold through the shaft 38 the rollers 27 in Contact with the guide face 20a. When nut 34 is loosened, shaft 31 is urged by resilient means 36 to the right as viewed in FIGS. 3 and 4, and the pressure between the rollers 27 and the stationary guide member 20 is increased.

It is evident that the guide rollers 26 and 27 of the movable guide means 24 and 25 guide the movable press plate 11 .along the parallel guide faces of the stationary guide means 19 and 20, so that press plate 11 is guided for movement along the central line of symmetry thereof. If the resistance of a workpiece between tools 5 and 14 is uniform along the entire length of the elongated edge faces of the tools, none of the springs 28 will be compressed. However, if the load on the movable press member is not entirely symmetrical with respect to its central line of symmetry, press plate 11 will tend to perform .a slight pivotal movement, resulting in yielding of the resilient means 36 on `one side of the central line of symmetry. A limit switch 41 with a feeler arm 41a is provided at least for the upper guide means 24 to sense Iany deviation of press plate 11 from its central position. As shown in FIG. 4, the arm 41a of limit switch 41 may engage the innermost cup-shaped spring 36, and will consequently respond to a compression of the spring caused by .a slight tilting of press plate 11. Limit switch 41 is connected into the `circuit of the electric motor of the compressor pump which pumps an operating liquid into the pressure chamber of cylinder 21, so that the motor is immediately stopped when press plate 11 tilts out of its normal position due to an uneven distribution of the load Ialong the length of the press edge-s. However, if the difference between the forces acting on the left and right of the central line of symmetry of press plate 11 is small, the pretensioned springs 28 will prevent undesired tilting movement-s of press plate 11.

In Aorder to accurately produce a desired angle in a workpiece, it is necessary to stop the press plate 11 at the end of its upward press stroke 'at an exact distance from the upper press edge yof tool 5. In accordance with the present invention, the pressure in cylinder 21 is automatically relieved when press plate 11 arrives in the desired upper terminal position.

`Referring to FIGS. 1, 2 and 5, ia pair of brackets 43 and 44 is mounted on plate 6, and supports in a bearing 45 and in a thrust bearing 46, a threaded spindle 47 which `can `be turned by hand wheel 48, so that a nut 49 which is mounted on a lever 50, travels along spindle 47 when hand wheel 48 is turned. Lever 50 is turnably mounted on a shaft 51 which is also supported by plate `6, and an arm 50a `of lever 50 projects into the path of movement of a rod 52 which is connected to la valve 53 in piston 22. The ball valve 53 is loaded by a spring 54 to close a lpassage 5S passing through piston 22 and 4connecting the pressure chamber in the lower part of the cylinder 21 with the discharge chamber in the upper part of cylinder 21. The inlet 56 is connected to a pump, and the outlet 57 is connected to a reservoir from which the pump sucks the operating liquid.

The upper terminal position of the press plate 11 is set by turning hand wheel 48 until the .adjustable stop lever 50 is in 1a desired position. When liquid is now pumped into cylinder 21, and piston 22 moves upward to push press plate 11 through force-transmitting member 23 in upward direction, rod 52 will abut stop lever 50 when press plate 11 approaches its upper terminal position. Rod 52 is displaced, and opens valve 53 against the action of spring 54 so that the liquid can ow from the pressure chamber below piston 22 to the discharge chamber above the piston and piston stops. By adjusting the positin of stop lever 50, the upper terminal position of press plate 11 can be exactly determined.

An adjustable lstop arrangement for determining the lower terminal position of press plate 11 is also provided, but not shown in FIGS. 1 and 2. The hydraulic apparatus used for this purpose will be described hereinafter with reference to the diagram of FIG. 18, which :also shows the above-described adjusting arrangement for the upper terminal position.

The embodiment of FIGS. 6 `and 7 is similar to the embodiment of FIGS. 1 and 2 and includes a support 1 with upright posts 2 `and 3, an upper press plate 4 mounted on posts 2 and 3, and a lower movable press plate 11 which is raised by a force-transmitting member 23 acting in the vertical center line of the movable press plate 11, and being operated by a piston in a hydraulic cylinder provided in -a prismatic guide member 20. Another guide member 19 is arranged above guide member 20, and the guide members 19 and 20 pass through corresponding cutouts 17 and 18 in the press plate 11 and are secured to the front plate 7 which is omitted in FIG. 6, but shown in FIG. 7. Slots 12 are provided in press plate 11, `and guiding means, not shown, corresponding to block 8 and rollers `9 and 10 described with reference to FIGS. 1 and 2, yare located in slots 12 to guide press plate 11. In the embodiment of FIGS. 6 and 7, a pair of 4rigid guide means 60 having a U-shaped cross-section are mounted on the vertical edges of slot 17 and have inner slide -faces 60a sliding Von the lateral guide faces of guide member 19 during movement of press plate 11. As best seen in FIG. 7, members 61 lare mounted on the vertical edges yof slot 18 and slidably engage the lateral guide faces 20a of guide member 20. Each member 61 consists of two parts 61a and 61b which are connected to each other by threaded bolts 62 passing through bores in press plate 11. Press plate 11 is located in the recesss formed by members 61a .and 61b :and has some play therein. Press plate 11 has two balls 64 in which balls 65 are located which have a diameter matching the width of recesss 63. The inner edges 1-8 of cutout 18 abut a part-cylindrical member 66 having a flat face abutting the flat bottom of recess 63. The construction of FIGS. 6 and 7 provides more rigid guidance along the center line of the movable press plate 11, but provides a certain freedom of movement of press iplate 11 in transverse direction .as indicated by arrows f and f'. An unsymmetrical work load will produce a pressure acting in the direction of the arrow F.

The stationary press member 4 is constructed of two outer plates 4a, and an inner plate 4b, as best seen in FIG. 8 where the outer front plate 4a is omitted for the sake of clarity. The upper part of the inner press plate 4b is of trapezoidal shape, so that the lateral oblique edges thereof expose pairs of slots 4c in the outer press plates 4a. Bolts 70 pass through slots 4c and are secured to upright supports 2 and 3 to carry the upper press member 4. Nuts 71 may be used for this purpose. Other bolts 72 pass through corresponding bores in the outer press plates 4a, and through registering bores 73 in the inner press plate 4b to support press plate 4b on the pair of outer plates 4a.

The axes of bolts 70 are spaced the distance L, while the bolts 72 are symmetrically arranged to a vertical plane of symmetry of the press plates, and are spaced the distance L/2.

FIG. 9 shows a diagrammatic illustration of this arrangement, wherein press plates 4a and 4b are represented by narrow rectangles, since the height of press plates 4a and 4b has no influence on the distribution of forces. Press plates 4a and 4b will be straight as illustrated in FIG. 9 when there is no load acting on the lower press edge of the inner press plate 4b.

When the resistance of the workpiece applies a pressure to the inner press plate 4b as indicated by the arrows W in FIG. 10, the forces will be transmitted through bolts 73 to the outer press plates 4a, which will be deformed as indicated in FIG. 10, since the lateral end portions of press plates 4a are supported by bolts 70. In this manner, a smaller maximum deformation of the ypress edge of the inner press plate 4b is obtained, as compared with an arrangement in which the entire press plate is supported only on the upright posts 2 and 3. The movable press plate 11 may also be constructed of two outer and an inner press plate, as described with reference to the stationary upper press plate 4.

Referring now to the embodiment of FIGS. 11 and 12, it will be seen that the general construction of this ernbodiment is similar to the construction described with reference to FIGS. 1 and 2. A support 1 has a pair of upright posts 2 and 3 carrying the upper press plate 4', and a pair of stationary plates 6 and 7 are secured to the support 1. The outer plates 7 is of rhomboidal shape and has lateral ends secured to the uprigh'ts 2 and 3, and a pair of guide means 19 and 20 are provided in the vertical plane of symmetry and connect plates 6 and 7. The lateral faces of members 19 and 2t) are parallel and are in contact with pairs of guide rollers 26 and 27. Guide rollers 26 are resiliently mounted, as best seen in FIG. 15. The cutout 11a of press plate 11 has a narrow cutout portion 11b in which a shaft 8-0 having two tiat faces is non-turnably located. Shaft carries at its ends the pair of rollers 26 which are constructed as ball bearings. A member 81 abuts at one end thereof shaft S0, and has two flanges 82 between which pairs of cup-shaped springs 83 are arranged, A threaded member 84 abuts through a member 85 and a spring 86 the edge of cutout 11a, and a nut 87 is threaded on member 84 and abuts a spring 83. Consequently, by turning of nut 87, the tension of spring 83 `can be adjusted and. the pressure between rollers 26 and guide member 19 exactly determined.

Rollers 27 are mounted on a member 88 which is secured to the lower edge of press plate 11. The shaft 89 of rollers 27 is non-turnably mounted, and may be pressed. by a threaded bolt 90 against guide member 20. However, as shown in FIG. 16, there are no springs provided to resiliently support rollers 27 so that rollers 27 cannot yield to lateral pressure produced by a tilting motion of press plate 11.

Guide member 20 has an inner cylinder chamber as described with reference to FIG. l, and a force-transmitting member 23 secured to the piston in the cylinder body 20. The upper end of force-transmitting member 23 abuts the top edge of cutout 18 in press plate 11 in the region of the central line of symmetry of press plate 11.

Five slots 12 are provided in press plate 11 and are bounded by guide members 13, as described with reference to FIG. 1. As best seen in FIG. 17, a pair of bolts 91 is secured to support plate 6, and carry two support blocks 92 carrying shafts 93 on which guide rollers 10 are turnably mounted. Guide rollers 10 roll on the guide bars 13 when press plate 11 moves up or down, and guide the same to prevent forward or rearward tilting of the press plate 11.

The upper press member 4' is mounted on projections 2a and 3a of the uprights 2 and 3, and secured to the same by threaded means 2b and 3b.

During operation of the press, a rigid guide means 27, 28 form a pivot axis which travels along the vertical plane of symmetry of press plate 11 and permits a pivotal movement of press plate 11. Such pivotal movement is opposed by the pretensioned resilient means 83, and when an undesired tilting of press plate 11 occurs, the arm 41a of limit switch 41 is displaced, as best seen in FIG. 15, and the motor of the pump is stopped so that no liquid under pressure is pumped into the pressure chamber of cylinder 20. The embodiment of FIGS. 11 and 12 is provided with adjustable stop means 50 as described With reference to FIGS. l, 2 and 5. Furthermore, adjustable hydraulic stop means for determining the lower terminal position of press plate 11 are provided, which are not shown in FIGS. 1l and 12 for the sake of simplicity, but which are shown in detail in FIG. 18.

The embodiment of FIG. 13 corresponds substantially to the embodiment described with reference to FIGS. 11, 12, 15, 16 and 17, but includes two additional hydraulic cylinder and piston means 100 which have force-transmitting members 101 secured to the pistons thereof. Force-transmitting members 101 have upper end portions abutting lateral portions of press plate 11 so that the press force is increased. Press plate 11 of the embodiment of FIG. 13 is guided in the same manner as press plate 11 of the embodiment of FIG. 11 by rigidly supported guide rollers 27 in its lower portion, and by resiliently supported guide rollers 26 in its upper portion.

The embodiment of FIG. 14 is similar to the above described embodiments and has rigidly supported guide rollers 27 in its lower part and resiliently supported guide rollers 26 in its upper part. Lateral cylinder and piston means 100 are provided, as in the embodiment of FIG. 13, and act on lateral portions of press plate 11. However, the embodiment of FIG. 14 includes a fourth cylinder and piston means 102 with a force-transmitting member 103 aligned with force-transmitting member 23 in the center line of symmetry of press plate 11, and having an upper end abutting the top edge of the cutout 117 in press plate 11. In this manner, the force acting on press plate 11 is further increased.

All the above-described embodiments are preferably provided with the hydraulic circuit and operating means illustrated in FIG. 18 which, however, shows two cylinders 100, one cylinder 102, and one cylinder 20, corresponding to the embodiment of FIG. 14. When FIG. 18 is applied to the embodiment of FIG. 13, the cylinder 102 is omitted, and when applied to the embodiments of FIGS. l and l1, cylinders and cylinder 102 are omitted.

As shown in FIG. 18, the foot pedal 16 is mounted for turning movement about a pivot point on a lateral wall of the machine. Lever 16 is articulated at 111 to a vertical link 112 and to another lever 16a which is mounted on the machine support for turning movement about a pivot point 16b. The end of lever 16a is articulated to a link 113 which is connected to a movable valve member 114 in a valve body 115 which has three ports controlled by a valve member 114. Port 117 is normally closed, and is connected to a conduit 119 communicating with the discharge conduit 120 of a pump 121 located in a reservoir 122 and being driven by an electric motor 123. When foot pedal 16 is depressed, valve member 113 is downwardly shifted while link 112 is upwardly shifted. In this position of valve member 114, pump 121 pumps the operating liquid through conduits 120, 119, and

ports 1.17, 116 into pressure conduit 125 which is connected to four parallel conduits 126 leading to the pressure chambers of the hydraulic cylinders 21, 100 and 102. As explained above, not all pressure cylinders are provided in the smaller embodiments of the invention.

The discharge openings 57 of the cylinders are connected by conduits 127 to a conduit 128 leading to the reservoir. FIG. 18 also shows the adjustable stop 50 cooperating with rod 52 of valve 53 of the cylinder means 20, 21. All cylinders 100 and 102 are provided with a corresponding valve construction, as schematically indicated by conduits 127 leading to cylinders 100 and 102.

A distributor valve means 130 includes a valve member 131 which is normally in an open position. When foot pedal 16 is depressed, link 112 raises valve member 131 and closes a passage in valve means 130. In the illustrated position, pressure liquid supplied by pump 121 passes through conduit 120 into a conduit 132 leading to another valve 133 which is normally closed, but can be opened to permit pressure liquid to enter the pressure meter 134. A spring loaded check valve 135 opens under the pressure of a liquid so that the liquid may pass through conduit 136 to the reservoir. However, when the valve member 131 is operated by foot pedal 116, this passage is closed and the pressure liquid is no longer circulated, but passes through conduits 119 and 125 since valve member 113 simultaneously opens the pressure passage in valve 115 so that pressure fluid flows through conduits 125 and 126, and operates the pistons in the pressure cylinders to move the press plate 11 in a press stroke until the .press plate 11 reaches its upper terminal position in which rod 52 abuts adjustable stop 50, and opens a passage 55- through piston 22 so that the pressure liquid can be returned through conduits 127 and 128 to the reservoir. When the operator releases foot pedal 16, pressure liquid is no longer supplied to the operating cylinders, and the weight of press plate 11 moves the force-transmitting members and pistons downward, while the pressure liquid passes out of the cylinders and through conduits 126 and 125 and ports 116 and 118 of valve 115 through a conduit 139, another valve means 140, and a conduit 141 into the reservoir.

Valve has an upper chamber in which a piston 143 is located, and a lower chamber communicating with conduits 139 and 141 and housing a valve member 144 which is normally in a position separating conduits 139 and 141. Piston 142 is connected by a link 14251 to the movable press plate 11, so that piston 142 moves up and down with press plate 11.

Another valve 150 is provided with a push button 151 controlling a spring-loaded valve 152 which is normally in a position preventing communication between a small container 154 for the operating liquid and the conduit 155 which is connected to the pressure chamber 143 in valve 140.

This valve arrangement serves for setting the lower terminal position of press plate 11.

When press plate 11 is raised by piston 22 and forcetransmitting member 23, for example, link 142er pulls piston 142 out of chamber 143 so that a vacuum is created in the same. When the table starts its downward stroke, piston 142 starts also to move into chamber 143, but at the same time oil is discharged from the pressure cylinders through conduits 126, 125, and 139 so that valve 144 is raised permitting the liquid to flow through conduit 141 into the reservoir 122. Valve member 144 can be raised, since there is still a negative pressure in chamber 143. When piston 142 has completely filled the vacuum in pressure chamber 143, valve 144 starts to move downwardly against the pressure of the liquid in conduit 139, and slowly moves to a closed position in which the downward movement of press plate 11 is stopped. In this manner, the last part of the downward motion of the table is dampened and slowed down.

For each displaced position of press plate 11, chamber 143 has a different effective volume dep-ending on the position of piston 142. When this volume is completely filled with pressure oil, the table cannot move any further down. Consequently, by iilling pressure chamber 143 with different volumes of oil at the beginning of operations, the lower terminal position of the press plate 11 can be determined. In order to set the lower terminal position of press plate 11, the operator depresses lever 16 in a preliminary operation, and when press plate 11 arrives in the position which is to be the lower terminal position during the following press operation, he stops press plate 11 by releasing the foot pedal 16. Press plate 11 is now at a standstill in its desired lower terminal position, and piston 142 projects to a certain extent into chamber 143. During this operation, a vacuum was created in chamber 143, and the operator now depresses push button 151 so that oil can flow from container 154 into chamber 143 and completely ll the same, whereupon push button 151 is released, and valve 152 closes. When a pressing operation is now performed, piston 142 will rise and create a vacuum in chamber 143, and when the table is permitted to perform its downward stroke, piston 142 will move downwardly into chamber 143. As explained above, when piston 142 completely iills the chamber 143 together with the oil previously supplied to the same, press plate 11 stops. Since oil was admitted by operation of valve 151, 152 in the chamber 143 in the position of press plate 11 which was desired as lower terminal position, press plate 11 will stop at the end of a pressing operation in the thus selected lower terminal position.

In all embodiments of the invention, limit switches 41 are provided to stop motor 123 when the press plate tilts out of its desired balanced position. Since the main pressure is applied by force-transmitting means `23 in the center line of the press plate 11, `its pressing edge will be deformed to form a curve whose center is higher than its end, and parallel to a corresponding hollow curve of -the upper press plate. In this manner, the workpiece is bent to an exact angle along the entire length thereof.

It will be understood that each of the elements described above, or two or more together, may also find a fuseful application in other types of presses differing from the types described above.

While the invention has been illustrated and described as embodied in a bending press having a centrally guided press plate and adjustable hydraulic means for determining the upper and lower terminal positions of the press plate, it is not intended to `be limited to the details shown, since 10 various moditications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that 1others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should fand are intended to be comprehended Within the meaning and range of equivalence of the following claims.

What is claimed as new and desired tol be secured by Letters Patent is:

1. In a press, in combination, -a movable press plate having an elongated edge face; moving means including at least one force-transmitting member oper-able in the direction of -a central line of symmetry substantially normal to said edge face of said movable press plate and engaging with one end thereof said movable press plate only in the center region thereof for moving said movable press plate in a working direction; irst and second stationary guide means extending in a said working direction substantially normal to said edge face of said movable press plate, and being spaced from each other :along said line; and tirst and second movable guide means carried by said movable press plate and being disposed so as to cooperate with said tirst and second stationary guide means, respectively, for guiding said movable press plate in said working direction, only one of said movable guide means being resilient and the other of said movable guide means `being rigid and cooperating with the respective stationary guide means in such a manner as to support said movable press plate during movement in said Working direction for pivotal movement about an axis transverse to said elongated edge of said movable press plate and to said working direction so that unequal forces acting on said edge face of said movable press plate tend to tilt said movable press plate about said axis while said resilient guide means yields.

I2. In a press, in combination, -a movable press plate having an elongated edge face; moving means including drive means and at least one force-transmitting mem-ber operable in the direction of `a central line of symmetry substantially normal to said edge face of said movable press plate and engaging with one end thereof said mov- .able press plate only in the `center region thereof for moving said movable press plate in a working direction; ,tirst and second stationary guide means extending in said working direction substantially normal to said edge face of said movable press plate, and being spaced from each other along said line; lirst 4and second movable guide means carried by said movable press plate and being disposed so as to cooperate with said first and second stationary guide means, respectively, for guiding said movable press plate in said working direction, only one of said movable guide means being resilient and the other of said movable guide means being rigid and `cooperating with the respective stationary guide means in such a man- 11er as to support said movable press plate during movement in said working direction for pivotal movement about an axis transverse to said elongated edge of said movable press plate and to said working direction so that unequal forces yacting on said edge face oi said movable press plate tend to tilt said movable press plate about said axis while said resilient guide means yields; and feeler means dispose between said movable press plate and said one movable guide means for sensing the relative position of the same, and adopted to move to an actuated position when said resilient means yield due to an undesired tilting of said movable press plate, said feelerl means .being operatively connected to said drive means to stop the same and thereby said movable press plate when moved to said actuated position.

3. In a press, in combination, a movable press plate having an elongated edge face; moving means including at least one force-transmitting member operable in the direction of a central line of symmetry substantially norrnal to said edge face of said movable press plate and engaging with one end thereof said movable press plate only in the center region thereof for moving said movable press plate in a working direction; rst and second stationary guide means extending in said working direction substantially normal to said edge face of said movable press plate, and being spaced from each other along said line, said first stationary guide means being spaced from said edge face of said stationary press plate a greater distance than said second stationary guide means; and first and second movable guide means carried by said movable press plate Iand being disposed so as to cooperate with said first and second stationary guide means, respectively, for lguiding said movable press plate in said working direction, said first movable guide ymeans being spaced from said edge face of said movable press plate a greater distance than said second movable guide means, being rigid, and cooperating with said first stationary guide means in such a manner `as to support said movable press plate during movement in said working direction for pivotal movement about an axis transverse yto said elongated edge of said movable press plate and to said working direction, and said second movable guide means being resilient so that unequal forces acting on said edge face of said movable press plate tend to tilt said movable press plate about said axis while said resilient guide means yields.

4. In a press, in combination, a movable press plate having an elongated edge face; moving means including at least one force-transmitting member operable in the direction of a central line of symmetry substantially normal to said edge face of said movable press plate and engaging with one end thereof said movable press plate only in the center region thereof for moving said movable press plate in a working direction; first and second stationary guide means extending in said working direction substantially normal to said edge face of said movable press plate, and being spaced from each other along said line, said first stationary lguide means being spaced from said edge face of said stationary press plate a greater distance than said second stationary guide means and being located in the region of said force-transmitting member; and first and second movable guide means carried by said movable press plate and being disposed so as to cooperate with said first and second stationary guide means, respectively, for guiding said movable press plate in said working direction, said first movable guide means being spaced from said edge face of said movable press plate a greater distance than said second movable guide means, being rigid, and cooperating with said first stationary guide means in such a manner as to support said movable press plate during movement in said working direction for pivotal movement about an axis transverse to said elongated edge `of said movable press plate and to said working direction, and said second movable guide means being resilient so that unequal forces acting on said edge face of said movable press plate tend to tilt said movable press plate about said axis while said resilient guide means yields.

5. In a press, in combination, a movable press plate having an elongated edge face; moving means including two force-transmitting members spaced from each other along and being operable in the direction of a central line of symmetry substantially normal to said edge face of said movable press plate and engaging with one end thereof said movable press plate only in the center region thereof for moving said movable press plate in a working direction; first and second stationary guide means extending in said working direction substantially normal to said edge face of said movable press plate, and being fixed on said support spaced from each other along said line, said first stationary guide means being spaced from said edge face of said stationary press plate a greater distance than said second stationary guide means, said first and second stationary guide means being respectively located in the region of said two force-transmitting members; and first and second movable guide means carried by said movable press plate and being disposed so as to cooperate with said first and second stationary guide means, respectively, for guiding said movable press plate in said working direction, said first movable guide means being spaced from said edge face of said movable press plate a greater distance than said second movable guide means, being rigid, and cooperating with said first stationary guide means in such a manner as to support said movable press plate during movement in said working direction for pivotal movement about an axis transverse to said elongated edge of said movable press plate and to said working direction, and said second movable guide means being resilient so that unequal forces acting on said edge face of said movable press plate tend to tilt said movable press plate about said axis while said resilient guide means yields.

6. In a press, in combination, a movable press plate having an elongated edge face; moving means including drive means and at least one force-transmitting member operable in the direction of a central line of symmetry substantially normal to said edge face of sai-d movable press plate and engaging with one end thereof said movable press plate only in the center region thereof for moving said movable press plate in a working direction; first and second stationary guide means extending in said working direction substantially normal to said edge face of said movable press plate, and being spaced from each other along said line, said first stationary guide means being spaced from said edge face :of said stationary press plate a greater distance than said second stationary guide means and being located in the region of said force-transmitting member; first and second movable `guide means carried by said movable press plate and being disposed so as to cooperate with said first and second stationary guide means, respectively, for guiding said movable press plate in said working direction, said first movable guide means being spaced from said edge face of said movable press plate a greater distance than said second movable guide means, being rigid, and cooperating with said first stationary guide means in such a manner as to support said movable press plate during movement in said working direction for pivotal movement about an axis transverse to said elongated edge of said movable press plate and to said working direction, and said second movable guide means being resilient so the unequal forces acting on said edge face of said movable press plate tend to tilt said movable press plate about said axis while said resilient guide means yields; and feeler means disposed between said movable press plate and said second movable 4guide means for sensing the relative position of the same, and adopted to move to an actuated position when said resilient guide means yield due to an undesired tilting of said movable press plate, said feeler means being operatively connected to said drive means to stop the same and thereby said movable press plate when moved to said actuated position, said drive means including an electric motor having a circuit and a switch in said circuit, said feeler means being operatively connected to said switch to interrupt said circuit and to stop said motor in said actuated position thereof.

'7. In a press, in combination, a movable press plate having an elongated edge face; moving means including at least one force-transmitting member operable in the direction of a central line of symmetry substantially normal to said edge face of said movable press plate and engaging with one end thereof said movable press plate only in the center region thereof for moving said movable press plate in a working direction; first and second stationary guide members spaced from each other along said line, each guide member having a pair of guide faces disposed symmetrically on opposite sides of said line and extending parallel to the same in said working direction and -spaced from the lateral ends of said movable press plate; first movable guide means including a pair of first rotary guide rollers carried by said movable press plate, said rst rollers being rigidly supported on said movable press plate and being located on opposite sides of said first stationary guide member in contact with said guide faces of the same so as to support said movable press plate for pivotal movement about an axis transverse to said elongated edge of said movable press plate and to said working direction; and second movable guide means including two carriers located on opposite sides of said second stationary guide member, two resilient means resiliently supporting said carriers on said movable press plate, and a pair of second rotary guide rollers respectively mounted on said two carriers for respectively engaging said guide faces of said second guide member and resiliently opposing pivotal movement of said movable press plate about said axis so that unequal forces acting on said edge face of said movable press plate tend to tilt said movable press plate about said axis while said resilient means yield.

8. In a press, in combination, a movable press plate having an elongated edge face; moving means including at least one force-transmitting member operable in the direction of a central line of symmetry substantially normal to said edge face of said movable press plate and engaging with one end thereof said movable press plate only in the center region thereof for moving said movable press plate in a working direction; first and second stationary guide members spaced from each other along said line, said first stationary guide member being spaced a greater distance from said edge face of said stationary press plate than said second stationary guide member, each guide member having a pair of guide faces disposed symmetrically on opposite sides of said line and extending parallel to the same in said working direction and spaced from the lateral ends of said movable press plate; first movable guide means including a pair of first rotary guide rollers carried by said movable press plate, said first `rollers being rigidly supported on said movable press plate and being located on opposite sides of said first stationary guide member in contact with said guide faces of the same so as to support said movable plate for pivotal movement about an axis transverse to said elongated edge of said movable press plate and to said working direction; and second movable guide means being spaced a smaller distance from said edge face of said movable press plate than said first movable guide means and including two carriers located on opposite sides of said second stationary guide member, two resilient means resiliently supporting said carriers on said movable press plate, and a pair of second rotary guide rollers respectively mounted on said two carriers for respectively engaging said guide faces of said second guidel member and resiliently opposing pivotal movement of said movable press plate about said axis so that unequal forces acting on said edge face of said movable press plate tend to tilt said movable press plate about said axis while said resilient means yield.

9. In a press, in combination, a movable press plate having an elongated edge face; moving means including 'drive means and at least one force-transmitting member operable in the direction of a central line of symmetry substantially normal to said edge face of said movable press plate and engaging with one end thereof said movable press plate only in the center region thereof for moving said movable press plate in a working direction; first and second stationary guide members spaced from each other along said line, each guide member having a pair of guide faces disposed symmetrically on opposite sides of said line and extending parallel to the same in said working direction and spaced from the lateral ends of said movable press plate; first movable guide means including a pair of first rotary guide rollers carried by said movable press plate, said first rollers being rigidly supported on said movable press plate and being located on opposite sides of said first stationary guide member in Contact with said guide faces of the same so as to support said movable plate for pivotal movement about an axis transverse to said elongated edge of said movable press plate and to said working direction; second movable guide means including two carriers located on opposite -sides of said second stationary guide member, two resilient means resiliently supporting said carriers on said movable press plate, and a pair of second rotary guide rollers respectively mounted on said two carriers for respectively engaging said guide faces of said second guide member and resiliently opposing pivotal movement of said movable press plate about said axis so that unequal forces acting on said edge face of said movable press plate tend to tilt said movable press plate about said axis while said resilient means yield; and feeler means disposed between said movable press plate and said second movable guide means for sensing the relative position of the same, and adopted to move to an actuated position when one of said resilient means yields due to an undesired tilting of said movable press plate, said feeler means being operatively connected to said drive means to stop the same and thereby said movable press plate when moved to said actuated position.

10. In a press, in combination, a movable press plate having an elongated edge face; moving means including at least two yieldable force-transmitting members spaced equal distances from said line and engaging said movable press plate .in the regions of the ends of said elongated edge face thereof; rst and second stationary guide means extending in said working direction substantially normal to said edge `face of said movable press plate, and being `spaced from each other along said line; and first and second movable lguide means carried by said movable press plate and being disposed so as to cooperate with said first and `second stationary guide means, respectively, for guiding said movable press plate in said working direction, one of said movable guide means being resilient and the other of said movable guide means being -rigid and cooperating with the respective stationary guide means in such a manner as to support said movable rpress plate during movement in said working direction for pivotal movement about an axis transverse to said elongated edge of said movable press plate and to ysaid working direction so that unequal forces acting on said edge face of 'said movable press plate tend to tilt said movable press plate about said axis while said resilient guide means yields.

i1. A bending press comprising, in combination, a pair of supports; a stationary press member including a pair of outer plates secured to said supports at the ends thereof, and an inner stationary press plate secured to said outer plates at two points inwardly spaced from said ends, said stationary press plate having an elongated edge face; Ia movable press plate having an elongated edge face confronting said edge face of said stationary press plate and being arranged -for movement toward and away from said edge fac-e of said stationary press plate; moving means including at least one force-transmitting member operable in the `direction of `a central line of symmetry substantially normal to said edge face of said movable press plate and engaging with one end thereof said movable press plate only in the center region thereof for moving said movable press plate toward said stationary press plate; rst and second stationary guide means extending in a working direction substantially normal to said edge face of lsaid movable press plate, and being fixed on said support spaced from each other along said line; and first and second movable guide means carried by said movable press plate and being disposed so as to cooperate with said first and sec-ond stationary guide means, respectively yfor guiding said movable press plate in said `Working direction, at least one of said movable guide means being resilient, and the other of said movable guide means being rigid and cooperating with the respective stationary guide means in such a manner as to support said movable press plate during movement in said working direction for pivotal movement about an axis transverse to said elongated edge of said movable press plate and to said working direction so that unequal forces acting on said edge face of said movable press plate tend to tilt said movable press plate about said axis while said resilient guide means yields.

12. In a press, in combination, a movable press plate having an elongated edge face; moving means including hydraulic cylinder and a piston in said cylinder `and having at least one force-transmitting member operable in the direction of a central line of symmetry substantially normal to said edge face of said movable press plate and engaging with one end thereof said movable press plate only in the center region thereof for moving said movable press plate in a working direction, said cylinder and piston having a valve means for relieving the operating pressure therein; an adjustable stop on said `Stationary press plate cooperating with said valve means for operating the same `during movement of said movable press plate so that said force-transmitting member and said movable press plate stop in a terminal position of said movable press plate selected by adjusting the position of said adjustable stop; first and second stationary guide means extending in a working direction substantially normal to said edge face of said movable press plate, and being spaced from each other along said line; and first and second movable guide means carried by said movable press plate and -being disposed so as to cooperate with said iirst and second stationary guide means, respectively, for guiding said movable press plate in said working direction, at least one of said movable guide means being resilient; and the other of said movable guide means being rigid and cooperating with the respective stationary guide means in such a manner as to support said movable press plate during movement in said working direction for pivotal movement about an axis transverse to said elongated edge of said movable press plate and to said working direction so that unequal forces acting on said edge face of said movable press plate tend to tilt said movable press plate about said axis while said resilient guide means yields.

13. In a press, in combination, a movable press plate having an elongated edge; iirst and second movable guide means secured to said press plate for movement with the same and spaced from each other along a line of symmetry passing through the center of said edge perpendicular to the same; and first and second stationary guide means spaced from each other along said line of symmetry and disposed to cooperate, respectively, with said first and second movable guide means for guiding said press plate for movement in a working direction perpendicular to said edge, at least said rst stationary and movable guide means being rigid in a direction transverse to said working direction.

i4. iin a press, in combination, a movable press plate having an elongated edge; first and second movable guide means secured to said press plate for movement with the same `spaced from each other along a line of symmetry passing through the center of said edge perpendicular to the same; and first and second stationary guide means spaced from each other along said line of symmetry and disposed to cooperate, respectively, with said first and second movable guide means for guiding said press plate for movement in a working direction perpendicular to said edge, one of said first guide means being resilient in a direction transverse to said Working direction, said second stationary and movable guide means being rigid, and said second stationary `guide means cooperating with said second movable guide means in such a manner as to support said movable press plate during movement in said working direction for pivotal movement about an axis transverse to said edge and to said working direction so that an unbalanced force acting on said edge of said press plate on one side of said line of symmetry tends to tilt said press .plate about said axis while said iirst resilient guide means yields.

15. In a press, in combination, a movable press plate having an elongated horizontal edge; first upper and second lower movable guide means secured to said press plate for movement with the same and and spaced from each other along a vertical line of symmetry passing through the center of said edge perpendicular to the same; and first upper and second lower stationary guide means spaced from each other along said line of symmetry and disposed to cooperate, respectively, with said iirst upper and second lower movably guide means for guiding said press plate `for movement in a working direction perpendicular to said edge, one of said first upper guide means being resilient in a direction transverse to said working direction, said second stationary and movable guide means being rigid, and said second stationary guide means cooperating with sai-d second movable guide means in such a manner as to support said movable press plate during movement lin said working direction for pivotal movement about an axis transverse to said edge and to said working direction so that an unbalanced force acting on said edge of said press plate on one side of said line of symmetry tends t-o tilt said press plate about said axis while said lirst resilient guide means yields.

i6. In a press, in combination, a movable press plate having an elongated horizontal edge; first upper and second lower movable guide means secured to said press plate for movement with the same and spaced from each other along a vertical line of symmetry passing through the center of said edge perpendicular to the same; and first upper and second lower stationary guide means spaced from each other along said line of symmetry and disposed to cooperate, respectively, with said first upper and second lower movably guide means for guiding said press plate for movement in a Working direction perpendicular to said edge, said rst movable upper guide means being resilient in a direction transverse to said working direction, said second stationary and movable guide means `being rigid, and said second stationary guide means cooperating with said second movable guide means in such a manner as to support said movable press plate during movement in said working direction for pivotal movement about an axis transverse to said edge and to said working direction so that an unbalanced `force acting on said edge of said press plate on one side of said line of symmetry tends to tilt said press plate about said axis while said rst movable resilient guide means yields.

i7. In a press, in combination, a movable press plate having an elongated edge; irst and second movable guide means secured to said press plate for movement with the same and spaced from each other along a line of symmetry passing through the center of said edge perpendicular to the same; first and second stationary guide means spaced from each other along said line of symmetry and disposed to cooperate, respectively, with said first and second movable guide means -for guiding said press plate for movement in a working direction perpendicular to said edge, one of said first guide means being resilient in a direction transverse to said Working direction, said second stationary and movable guide means being rigid, and said second stationary guide means cooperating with said second movable guide means in such a manner as to support said movable press plate during movement in said working direction for pivotal movement about an axis transverse to said edge and to said Working direction so that an unbalanced force acting on said edge of said press plate on one side of said line of symmetry tends to tilt said press plate about said axis while said rst resilient guide means yields; moving means acting in said line of symmetry for moving said press plate in said Working direction; and lfeeler means for sensing a tilted position of said press plate and operatively connected with said moving means for stopping the same when said press plate moves to a tilted position.

References Cited by the Examiner UNITED STATES PATENTS 10/1938 Schade 153-21 5/ 1945 Hess 100-269 X 6/1951 Castle 153-21 X 11/1961 Giordano s 153-21 FOREIGN PATENTS 2/ 1952 Great Britain. 8/ 1958 Great Britain. 

1. IN A PRESS, IN COMBINATION, A MOVABLE PRESS PLATE HAVING AN ELONGATED EDGE FACE; MOVING MEANS INCLUDING AT LEAST ONE FORCE-TRANSMITTING MEMBER OPERABLE IN THE DIRECTION OF A CENTRAL LINE OF SYMMETRY SUBSTANTIALLY NORMAL TO SAID EDGE FACE OF SAID MOVABLE PRESS PLATE AND ENGAGING WITH ONE END THEREOF SAID MOVABLE PRESS PLATE ONLY IN THE CENTER REGION THEREOF FOR MOVING SAID MOVABLE PRESS PLATE IN A WORKING DIRECTION; FIRST AND SECOND STATIONARY GUIDE MEANS EXTENDING IN A SAID WORKING DIRECTION SUBSTANTIALLY NORMAL TO SAID EDGE FACE OF SAID MOVABLE PRESS PLATE, AND BEING SPACED FROM EACH OTHER ALONG SAID LINE; AND FIRST AND SECOND MOVABLE GUIDE MEANS CARRIED BY SAID MOVABLE PRESS PLATE AND BEING DISPOSED SO AS TO COOPERATE WITH SAID FIRST AND SECOND STATIONARY GUIDE MEANS, RESPECTIVELY, FOR GUIDING SAID MOVABLE PRESS PLATE IN SAID WORKING DIRECTION, ONLY ONE OF SAID MOVABLE GUIDE MEANS BEING RESILIENT AND THE OTHER OF SAID MOVABLE GUIDE MEANS BEING RIGID AND COOPERATING WITH THE RESPECTIVE 